The present invention relates to a novel polymer curable by moisture to convert into an elastomeric material or a resinous material, and a pressure sensitive adhesive composition.
Organic polymers having in the molecule at least one reactive silicon functional group are obtained according to the process proposed, for instance, in Japanese Examined Patent Publication (Tokkyo Kokoku) No. 36319/1970, No. 12154/1971 and No. 32673/1974 and Japanese Unexamined Patent Publication (Tokkyo Kokai) No. 156599/1975, No. 73561/1976 and No. 6096/1979, and some of them are commercially available from Kanegafuchi Kagaku Kogyo Kabushikikaisha under the commercial name of "Kaneka MS Polymer". It is known that these organic polymers are curable by moisture and suitable for use in paints, adhesives, sealants, etc. However, these organic polymers have drawbacks resulting from the structure of the main chain and from the manner of bonding of the reactive silicon functional group to the main chain. For instance, the polymer proposed in Japanese Unexamined Patent Publication No. 73561/1976 is poor in weather resistance because it has urethane bonds in the main chains and the chain ends and also has a problem in workability because of a very high viscosity resulting from hydrogen bonds by urethane bonds. The polymer proposed in Japanese Unexamined Patent Publication No. 156599/1975 has a problem in weather resistance resulting from hydrogen atoms bonding to tertiary carbon atoms of the polyether main chain.
Conventional pressure sensitive adhesives are classified roughly into rubber adhesives, acrylic resin adhesives, silicone adhesives, and the like. The rubber adhesives are superior in tack (initial tackiness), but poor in weather resistance and heat resistance. On the other hand, the acrylic resin adhesives are superior in weather resistance and heat resistance, but poor in initial tackiness.
The silicone adhesives have less drawbacks than the rubber or acrylic resin adhesives and are superior in performance, but the use of them are limited because of their high price. For the purpose of eliminating the above-mentioned drawbacks, there is proposed a pressure sensitive adhesive composition containing a natural or synthetic rubber onto which a polymerizable monomer such as an acrylate or styrene monomer is graft-polymerized, but this purpose is not attained sufficiently. Conventional rubber adhesives have a problem in environmental sanitation or safety because the adhesives require a large amount of solvent as well as the acrylic resin adhesives, and further these adhesives are prepared by a complicated mechanical process such as a mastication.
It is an object of the present invention to provide a novel moisture-curable polymer having excellent weather resistance.
A further object of the invention is to provide a cheap pressure sensitive adhesive composition which scarcely requires solvent for dilution and which contains a polymerized product curable to convert into a rubber-like material or a resinous material having excellent inital tackiness, heat resistance and weather resistance.
These and other objects of the present invention will become apparent from the description hereinafter.